Multilayer photographic element for color photography



United States Patent 3,211,552 MULTILAYER PHQTOGRAPHIC ELEMENT FQR COLOR PHOTOGRAPHY Victor Fu-Hua Chu, East Brunswick, John Charles Firestine, South River, and Jacob Quentin Umberger, Holmdel, N.J., assignors to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware No Drawing. Filed May 29, 1961, Ser. No. 113,100

3 Claims. (CI. 96-74) This invention relates to color photography and more particularly to multicolor elements for chromogenic development.

In a multilayer color film, e.g., monopack or integral tripack, it is theoretically impossible for that portion of the image recorded in the inner or lower layers to be equivalent, in such qualities as sharpness and resolving power, to images recorded in monolayer films. The use of color separation negatives permits each image record to be carried in an outer layer, but the problems of image registration in printing have created a greater demand for the monopack multicolor films. Such films are essential for multicolor reversal processes using color development.

In an article by I. Eggert and W. Grossman, The Resolving Power of Three-Layer Color-Films, Naturwissenschaften, 39, No. 6, 132-133 (1952), it has been shown that it is not the form in which the coupler (color former) is present during the color-forming process which is the predominant influence on resolution, but it is the light diffusion within the layer during exposure that is important. Resolution is reduced with a greater layer depth. In describing layer depth, these authors have defined the term (6) which equals the distance from the surface of the outermost photosensitive layer to onethird into the innermost photosensitive layer. Eggert and Grossman have measured resolving power in a number of commercial multicolor films and have found high resolving power figures for those types of color film which are processed in developers containing color-formers. Multilayer color films in which color-formers were incorporated into the emulsion layers gave consistently lower values of resolving power which is correlated with their greater critical thicknes, 6. Thus, the advantages of film elements containing color-formers, in terms of simplicity of development, must be weighed against the advantages of film elements to be processed in developers containing color-formers which, by virtue of their thinness, give superior results in terms of resolution, definition, etc.

An object of this invention is to provide improvements in the field of photography and more particularly in multilayer elements for chromogenic development. Another object is to provide multilayer color films for chromogenic development which have both high resolving power values and the processing simplicity of integral coupler emulsions. A further object is to provide such films which can be readily made by using conventional chemical apparatus, and aqueous coating and drying apparatus. A still further object is to provide high-speed color reversal films of the foregoing types. Still further objects will be apparent from the following description of the invention.

The improved multicolor elements of this invention comprise a support, e.g., film, plate or paper, bearing a plurality (preferably three) of differentially sensitized silver halide emulsion layers having an integral emulsion thickness (6) not more than 12.5 microns and preferably 7.6 to 12.5 microns, each adapted to record images from light in a different region of the visible spectrum and containing a water-permeable binder comprising gelatin and a compatible color-forming vinyl addition polymer containing a plurality of color-former nuclei capable of forming a quinoneimine, azomethine or an azo dye upon color-coupling development of a silver salt image, the etfective color-forming equivalent weight of the binder being not more than 1750, preferably 5001750, said addition polymer also containing a plurality of watersolubilizing anionic groups so that the polymer remains in solution in water at 25 C. and pH 7.0 to the extent of .at least 40 grams per liter with a viscosity of 1.5 to 15 centistokes. The modified gelatino-silver halide emulsion layers may contain, as shown in the working examples below, about 7 to 25 parts by weight of the compatible color former per about 10 to 30 parts by weight of gelatin. The color-former nuclei are extralinear, being linked to a carbon atom of the wholly carbon chain by various linkages including amide, ether and cyclic acetal linkages. The pH can be adjusted by addition of alkali, e.g., NaOH, KOH, Na CO or K CO In these films, the thickness, 8, is as defined in the Eggert and Grossman reference.

The novel elements of the invention may also contain a yellow filter stratum or layer and, in the case of color reversal films, the blue-sensitive layer should be outermost and the remaining silver halide layers adapted to record in the red and green regions of the spectrum being disposed in any order and preferably all on the same side of the support. The color-formers in the blue, green and red regions of the spectrum, in general, should yield dyes upon development complementary in color to the utilized sensitivity of the respective silver halide emulsion layers.

By equivalent weight is meant the number of grams of color-forming polymer containing one gram molecular weight of the active color-forming nucleus or coupling group, e.g., reactive methylene group. The equivalent weight can be determined from ultraviolet spectral analysis of a solution of the anionic color-former, as follows:

(1) Weigh out a 0.4 to 0.6 g. sample on an analytical balance and record weight to the nearest 0.0001 g.

(2) Quantitatively rinse into a one-liter volumetric flask with alcohol.

(3) Add 40 ml. of 5% sodium hydroxide and heat with occasional shaking until the solid dissolves.

(4) Cool to 20 C. and dilute to one liter with distilled Water at 20 C.

(5) Add a 10 ml. aliquot into a 200 ml. volumetric flask and dilute with 0.1 N sodium hydroxide at 20 C.

(6) Immediately obtain the optical density of the solution vis. distilled water at the absorption peak near 353 m for cyan, 330 m for yellow and 260 m for magenta. Use a one cm. silica cell and a standard spectrophotometer.

(7) Calculated the equivalent weight from the following formula:

Wt. of sample in grams x E D X 20 where E is the molar extinction coefficient of the color- 13 forming nucleus or monomer. The coefficient E is defined in Glasstone, Textbook of Physical Chemistry, 2nd edition, 1946, D. Van Nostrand, New York, page 581.

The effective coupling equivalent weight is a measure of the efiiciency of the total binder-color-former system, in yielding thin color emulsions. It is defined as the quotient obtained when color-former equivalent weight is divided by the fraction of the total binder comprised of color-former. The lower the effective equivalent Weigh the more efficient is the color-former in forming thin layers. The thickness, A, has been defined above in reference to the article by Eggert and Grossman.

In accordance with a further aspect of the invention, at least one of the gelatin/col-or-forming polymer silver halide emulsions can have admixed therewith a plasticizer, e.g., glycerine, diethylene gylcol, triethylene glycol, tricresyl phosphate, dimethyl sebacate, dioctyl phthalate (Flexol DOP), triethylene glycol di-Z-ethylhexoate, ethyl phthalyl ethyl glycolate, and oand p-toluene ethyl sulfonamide.

The preferred color-forming elements of the invention also contain a flexibilizing polymer which acts as a third binder component. For best performance, this third binder component should be an addition polymer of relatively low melting point and free from ionized groups and primary amide groups. This third polymer component acts as a co-binder for silver halide along with gelatin and the compatible polymeric color-former. Eifective equivalent weight is as defined previously, whether for a twoor a three-component binder system, and the same upper limit of 1750 applies. This third binder may be liquid and water-soluble at 25 C., i.e., liquid copolymers of ethylene and propylene oxides with Saybolt viscosities of 900 to 90,000 Universal seconds are useful, but preferably is water-insoluble and is present in the form of a dispersion of small, solid particles having an average diameter of less than l-micron. The mixed binder comprised of gelatin, polymeric colorformer, and flexibilizing polymer forms a continuous blend when the dry film is viewed under an ordinary microscope.

Silver halide emulsion layers having the three-component binder have the advantage over layers containing two component binders in that they have improved flexibility and reduced tendency to curl. The layers, moreover, can be made uniform in image-yielding properties and extremely thin, e.g., in the order of 2.5 to 5.0 microns.

Useful polymeric color-formers contain recurring colorformer nuclei and recurring anionic grougs, e.g., carboxylic or sulfonic acid groups or the corresponding Na, K, NH amine or quaternary ammonium salts, which confer water-soluble properties to the color-former. Color-formers of this type, for example, may be vinyl or vinylidene type addition polymers having a wholly carbon chain or backbone to which there are attached extralinear groups containing the solubilizing groups and the color-former nuclei. By color-former nuclei are meant nuclei containing groups which are capable of coupling with oxidation products or aromatic primary amine developing agents, e.g., p-phenylenediamine, formed during the development of silver salt images, to form a quinoneimine, azomethine or in some instances an azo dye image. In preferred color-formers, the nuclei have a structure which may be represented by the formula:

where I X is =CH, 3C1, 3Br, 3S0 H, or =l\ l which is a general structure of the color-coupling nucleus in an enol form. I

The foregoing nuclei are found in the reactive methylene dye intermediates and in aromatic hydroxyl compounds and includes the reactive ethanol groups. These groups occur in phenols, naphthols, acylacetamides, cyanoacetyles, beta-ketoesters, pyrazolones, homophthalimides, coumaranones, indoxyls, thioindoxyls, and indazolones.

Polymeric color-formers having the prescribed low equivalent weights which satisfy the above requirements include those disclosed in Firestine and Umberger, Ser. No. 21,959 filed April 3, 1060 (US. Patent 3,163,625, Dec. 29, 1964), and those obtainable by substituting for the l-phenyl-3-methacrylamido-5-pyrazolone monomeric reactant in the processes thereof, p-(cyanoacetyl)methacrylanilide or 6-methacrylamidoindazolone; in Schoenthaler and Warfield, Ser. No. 586,636 filed Sept. 27, 1960, abandoned and replaced by continuation-in-part application Ser. No. 394,040, filed Sept. 2, 1964, and in Umberger application for Dye Intermediates, Ser. No. 113,101, abandoned Dec. 17, 1964, and replaced by application Ser. No. 419,227, Dec. 17, 1964) filed May 29, 1961. Additional suitable color-forming intermediates from which suitable color-formers can be made are disclosed in McQueen, U.S. Patent 2,464,597. Useful polyvinyl acetal color-formers can be prepared having a high degree of substitution, both of color-forming nuclei and of water-solubilizing groups, by carrying out the substitution reaction at relatively low temperatures with short reaction times in the absence of acetone which tends to promote cross-linking and by maintaining the polymer in solution form instead of drying it after synthesis .and prior to use for coating in a photographic emulsion. These precautions are desirable to produce the desired low equivalent weight polymers, since the active methylene groups of the color-forming nuclei are particularly subject to intermolecular cross-linking reactions when they recur at the high frequency required by this invention.

Thus, two methods have been found for preventing the undesirable cross-linking reactions normally encountered in the preparation of color-forming polymers with frequently recurring color coupler groups:

(a) Attachment of the color-coupling nuclei or side groups to a pre-formed polymer under reaction conditions with the polymer reactant completely dissolved in a non-cross-linking reaction medium and with relatively low reaction temperature and short time. The resulting polymer is kept in the Wet, i.e., solution, state in the interval between its synthesis and its addition to the gelatino-silver-halide emulsion for coating.

(b) Attachment of the color-coupling nuclei or side group to an addition polymerizable vinyl monomer by chemical reaction and purification steps prior to the free radical or ionic-initiated addition copolymerization of the resulting color-forming monomer.

It is to be emphasized that when the prior art methods of preparing polymeric color-formers are used at the limit of high reaction temperature, time, and concentration in order to achieve the necessary high degree of color-former substitution, the resulting polymers are gelled or so viscous as to be impractical, especially for coating from the concentrated emulsions required for high-speed coating methods.

According to a further aspect of the invention, after the first non-color-forming development, the film element is re-exposed to light and then developed in an aqueous alkaline developer solution of the type disclosed in Example I of Jennings US. Patent 2,397,865, Apr. 2, 1946. However, any of the other color-developing agents described in said Jennings patent can be used. The preferred developer solutions, however, have a higher content of sodium sulfite and contain 20 to 60 grams of sodium sulfite (anhydrous basis) per liter of solution. These solutions have the advantages set forth in Example IV.

The color developer solutions may also contain a small proportion of an organic solvent, e.g., benzyl alcohol, benzyl amine, dimethyl formamide, to insure solubility of the developing agent and to insure full development of maximum dye density, particularly in emulsions relatively high in their ratio of synthetic polymer to gelatin.

Elements made up of integral coupler emulsions obviously become more susceptible to interlayer color contamination (particularly the contamination due to migration of oxidized developer during the color development step) as the emulsion layers become thinner. It has been found that this color contamination can be effectively reduced by the addition of a competing coupler, e.g., phenols that form a soluble removable dye on coupling (such as citrazinic acid). In particular, it has been found that the larger concentrations of sodium sulfite prescribed above in the color developer solutions are especially effective in combination with the polymeric bindercolor formers in reducing interlayer color contamination caused by migration of oxidized developer and by migration of color-former molecules.

Useful low melting, non-ionized, synthetic vinyl polymers, capable of serving as a co-binder with gelatin and a polyanionic color-former to improve the flexibility of the film, include the preferred class of alkyl acrylates and methacrylates, e.g., polymers and copolymers of methyl, ethyl, butyl, ethylhexyl acrylate and methyl and butyl methacrylate. In addition, acrylic acid can be used in small amounts in the preparation of the copolymers in order to modify properties of the copolymer. Other polymers can be made from the vinyl esters, such as the acetate, propionate, etc., the vinyl and vinylidene halides such as vinylidene chloride; styrene and substituted styrenes; the dienes such as butadiene; acrylonitrile; alkenes such as ethylene or propylene, and the like.

These water-insoluble polymers are added as dispersions of fine particle size obtained by techniques of emulsion polymerization known in the art, such as the use of adequate concentrations of surfactants, the mode of stirring, the concentrations of reactants, temperature, rate of addition of monomer, etc., and by dispersing a preformed polymer, e.g., polyethylene, with suitable surfactants. Preferred amphoteric dispersing agents and procedures for preparing the dispersions are disclosed in Nottorf, U.S. Ser. No. 94,989 filed March 13, 1961. Also useful as dispersing agents are other amphoteric compounds such as betaines, e.g., C-cetyl betaine, taurines, glycines, etc., as well as the anionic dispersing agents such as sodium dodecyl sulfate, dodecylbenzene sulfonic acid, naphthalenesulfonic acid condensed into a polyanion with formaldehyde, sodium isopropylnaphthalene-sulfonic acid and sodium dioctylsulfosuccinate.

In exemplification of the invention, a hydrophobic film support, e.g., cellulose acetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetatebutyrate, etc., or a superpolymer such as nylon, polyvinyl chloride, polyester, e.g., polyethylene terephthalate, polycarbonate, etc., glass, wood, paper, etc., suitably subbed to provide proper adhesion with layers to be coated thereon, is coated on one surface with a non-halation layer comprising gelatin in which there is dispersed colloidal silver capable of absorbing light of all visible wavelengths. Coated in order on the non-halation layer are a gelatinosilver halide emulsion layer sensitive to blue and red light and containing a polyanionic cyan color-former, a gelatin separator layer, a gelatino-silver halide emulsion layer sensitive to blue and green light and containing a polyanionic magenta color-former, a gelatin layer containing a blue light-absorbing material, e.g., colloidal silver, a gelatino-silver halide emulsion layer sensitive to blue light and containing a polyanionic yellow colorformer, and a gelatin anti-abrasion layer. It is to be understood that the silver halide layers have the characteristics and thickness defined above.

The light-sensitive emulsion layers may be arranged with respect to the support in other manners and with other arrangements of spectral sensitivities and colorformers as is known in the art. Suitable other layer arrangements are disclosed in U.S. Patents 2,397,864, 2,927,019 and 2,927,024, and in assignees Blanchard U.S. application Ser. No. 672,495 filed July 17, 1957 (U.S. Patent 2,997,388, Aug. 22, 1961). However, the advantages of the thin emulsion layers of this invention will be most appreciated in a configuration in which the uppermost light-sensitive layer contains a yellow color-former.

The invention will be further illustrated by but is not intended to be limited to the following examples. It is to be understood that some of the films to be described are convenient for testing various materials for use in making the thin emulsion layers which result in the observed improvements in such qualities as resolution and definition. It is not represented that these simplified structures (i.e., films capable of recording only in the blue and green region of the spectrum) have any commercial utility as multilayer color films.

EXAMPLE I Investigation of the effect of thickness of the outer blue record emulsion and the separator layers on the resolving power and sharpness of the inner record emulsion was carried out. Three multilayer photographic films, A, B, and C of structures and coating weights shown below were prepared.

All were coated on cellulose triacetate base with a nonsalation tint of optical density about 0.3.

The resolving power data on the green record layers of these films were obtained by exposing with a green filter through the blue record emulsions on an Eggert Resolvometer, described in Proceedings of the Royal Photographic Soc. Centenary Conference, London [1953], p. 292.. On development in a standard metolhydroquinone developer with sodium carbonate as the activating base, fixing in a standard acid-hardening sodium thiosulfate solution, washing and drying, it was found that Film C, with no blue record emulsion, resolved 100 lines per millimeter; Film A, with a thin blue record emulsion and a thin separator layer, resolved lines per millimeter; and Film B, with relatively thick blue record emulsion and thick filter layer, resolved only 60 lines per millimeter.

Having established and confirmed the value of total emulsion thickness in achieving photographic images of high resolving power, sharpness, and definition, especially in multilayer films as employed in color photography, it was next established that the photosensitive silver halide crystals add little to the emulsion thickness due to their low specific volume. The organic components, gelatin and polymeric color-former, composed of lighter atoms, were found to be the main contributors to emulsion thickness. It was found that, by replacing part of the binder gelatin by new synthetic polymeric bindercolor-formers, thin emulsions of high definition were obtained. These synthetic polymeric color-formers are highly substituted with color-coupling lateral or side groups in order to achieve advantageous thin emulsion layers. The photosensitive silver halide crystals are still formed in a limited amount of gelatin to effect the ripen- 7 ing and sensitizing of gelatino-silver halide emulsions. The blend of gelatin and polymeric color-former constitutes a continuous phase (on a microscopic scale) and together with the two polymers, one of natural origin and the other synthetic, share the binder function for the silver halide crystals.

In the examples of complete color films that follow, definition will be rated in terms of S-mm. motion picture projection test as a more reliable guide than resolving power in lines per millimeter.

Also, the color developers employed in processing are unusually high in sodium sulfite content, viz., 20 to 60 grams of anhydrous Na SO are employed per liter of developer solution as compared with the more normal range 2 to grams per liter employed heretofore. Surprisingly, the high-sulfite color developers help to prevent interlayer color contamination caused by migration of color-formers and oxidized developer molecules and yield processed film free from haze due to prevention of excessive emulsion swelling in alkaline developers. Most surprising is the fact that a significant dye density is obtained in View of the known action of sulfite ion to prevent color-coupling by reacting with oxidized developer. Indeed, some loss of dye density occurs with the high sulfite developer solutions, but this is readily corrected by adjustment in coating weight of the emulsion layers to yield proper maximum density in these new developers. The loss in density encountered above is actually advantageous in that the appearance of image graininess is lessened due to competing action to prevent excessive density intensification during the dye-forming process. We find high sulfite developers simpler in composition than those containing citrazinic acid, also less colored, and with the additional advantage of controlling emulsion swelling and polyanion color-former migration referred to previously.

It will be noted a further route to decreased interlayer color contamination in the thin emulsions of this invention is described in assignees copending application, Evans and Umberger Ser. No. 113,285 filed may 29, 1961, disclosing polycation-gelatin separator layers to decrease the interlayer migration of the polyanion colorformers.

EXAMPLE II Four multilayer color reversal photographic film elements were prepared having a conventional structure comprising the following:

(a) A cellulose triacetate photographic film base support having a conventional substratum and coated thereon a non-halation layer comprised of 7 rng./dm. of bone gelatin and 3.5 mg./dm. of a colloidal silver dispersion absorbing light of all visible wave lengths.

(b) A gelatino-silver bromo-iodide emulsion layer sensitive to blue and red light containing 3.4 mole percent silver iodide and 96.6 mole percent silver bromide and containing, per mole of silver halide, one eighth of a mole of polyanion cyan color-former. Film 1 employed a polyanion cyan color-former of the polyvinyl ether type, shown in Example I of assignees copending Umberger application entitled, Dye Intermediates, Ser. No. 113,101 filed May 29, 1961 (abandoned Dec. 17, 1964, and replaced by application Ser. No. 419,227, Dec. 17, 1964), which was dissolved in aqueous alkali to hydrolyze the maleic anhydride ring. In Table I are further data on the cyan color-formers. Film 2 employed a polyanion cyan color-former of the polyvinyl acetal type described in Example I of assignees Schoenthaler and Warfield application Ser. No. 58,636, filed Sept. 27, 1960 (abandoned Oct. 24, 1964, and replaced by continuation-in-part application Ser. No. 394,040 filed Sept. 2, 1964). Film 3 employed a polyanion cyan color-former of the polyrnethacrylhydrazide type prepared by a procedure similar to that shown in Example I of assignees copending application of Firestine and Umberger U.S. Ser. No. 21,959,

g. filed April 13, 1960 (U.S.P. 3,163,625), by. copolymerizing 1 mole of the compound of the formula with 1.25 moles acrylic acid and 0.75 mole acrylamide.

Table 1 Color E fiective Polyanion Cyan CF Equiv. former Gelatin AgX Equiv.

weight ctg. wgt., ctg. wt. ctg. wgt. mgJdm. wgt.

Polyvinyl ether- 390 9 18 34 1, Polyvinyl acetal 760 17 18 34 1, 570 Polymethacrylhydrazide 420 10 18 84 l, Polymethacrylamide 410 8. 5 16 30 1,

(c) A separator layer comprised of a solution of bone gelatin containing the normal additives, saponin surfactant plus chrome alum hardener, coated over all of Films 1, 2, 3 and 4 at a coating weight of 20 mg. gelatin/ dm.

(d) A gelatin-silver bromo-iodide emulsion layer sensitive to blue and green light containing 3.4 mole percent silver iodide and 96.6 mole percent silver bromide and containing a polyanion pyrazolone magneta color-former of the type shown in assignees copending application U.S. Ser. No. 21,959, filed April 13, 1960 (U.S. Patent 3,163,625, Dec. 29, 1964), but reducing the proportions of acrylic acid and acrylamide to 1.25 moles and 0.75 mole, respectively, per mole of color-forming monomer, to yield a color-former having an equivalent weight of 350. The coating weights of Ag halide, gelatin and colorformer were 32 mg./dm. 17 mg./dm. and 9.6 mg./ dm. respectively, and effective coupling equivalent weight was computed to be 970.

(e) A gelatin colloidal silver intermediate layer for absorbing blue light coated at 10 mg./dm. of gelatin and 1.3 mg./dm. of yellow colloidal silver.

(f) a gelatino-silver bromo-iodide emulsion layer sensitive to blue light containing 1.7 mole percent silver iodide and 98.3 mole percent silver bromide and containing a polyanion benzoylacetanilide yellow colorformer prepared by transacetalization of 100 parts of low viscosity 99% hydrolyzed polyvinyl alcohol with 120 parts of m-benzoylacetamidobenzaldehyde ethylene glycol acetal and 50 parts of o-sulfobenzaldehyde in an ethanol-water reaction medium with p-toluenesulfonic acid to pH 1.7 as acetalization catalyst to yield a color-former of 775 equivalent weight. The coating weights of silver halide, gelatin, and color-former were 25 mg./dm. 10 mg./dm and 25 rng./drn. respectively, which is computed to be 1090 effective coupling equivalent weight.

(g) A gelatin anti-abrasion layer of coating weight 10 mg./dm. bone gelatin and 1.5 mg./dm. of an ultraviolet absorber derived from 2,2-disulfo-4,4'-diaminostilbene.

The four films just described were slit to a width of 32 mm., conventionally perforated, slit to 16 mm. width and exposed in an S-mm. camera. The films were processed by reversal with all solutions at 70 F. First they were developed in a conventional black and white, pmethylaminophenolhydroquinone developer, then treated with an acid shortstop bath, water washed, and re-exposed by flashing to white light. They were then color developed for 20 minutes in a solution containing ten grams per liter of the color developing agent, 4-amino-N-ethyl-N- (beta methanesulfonamidoethyl)-m-toluidine sesquisulfate monohydrate, 40 grams per liter Na PO .l2 H 0, and 20 g. per liter (Anhy.) Na SO Processing was continued with another acid shortstop treatment, washing with water, bleaching, washing, fixing with sodium thiosulfate, washing and drying.

The four films were compared for image definition by projecting on a screen using, as a control, a commercially available S-mm. color reversal film with non-integral couplers, i.e., a film processed with the couplers in the developer solutions. The 8-mm. screen projection, a severe test for image definition, showed the four coatings essentially equivalent to the control. This is a consequence of similar total emulsion thickness determined to be about 15 microns (excluding the antihalation layer) for all five films including the control.

This is equivalent to a value of less than 12.5 microns for the distance 5 of Eggert and Grossman from the top of the yellow emulsion to /a into the cyan since the cyan emulsions and anti-abrasion layers total to about 3.8 microns in thickness. It is significant that all of the polyanion color-formers had effective coupling equivalent weights under 1750. Nowhere does the prior art show such low elfective coupling equivalent weights.

An additional film was prepared in which the only change was the substitution, for the polyvinyl acetal yellow color-former, of a polymethacrylamide yellow prepared by copolymerizing 1.0 mole benzoylacet-2-chloro-4- methacrylanilide with 2.0 moles acrylic acid to yield a color-former of equivalent weight 610, thus illustrating another linkage for the yellow coupler. This polyanion required more gelatin to add binder action than did the polyvinyl acetal to avoid the processing haze likely to form in the outer emulsion which is subject to considerable washing action during processing. The abrasion layer was doubled in thickness of gelatin and hardened with chrome alum plus formaldehyde rather than just chrome alum as in the previous examples, and thus clear S-mm. projection results were obtained after exposure and processing. The actual coating weights employed for this yellow emulsion were 20 mg/dm. silver halide, 30 rng./dm. gelatin, and 16 mg./dm. color-former. These data yield an eifective coupling equivalent Weight computed to be 1750.

EXAMPLE III A film was coated similar to Film 1 of Example II but with the addition of 12 mg./dm. of polyethylacrylate to the cyan layer, 6 mg./dm. to the magenta layer, and 15 mg./dm. to the yellow emulsion layer. The polyethyl acrylate was added as a 30% by weight aqueous dispersion using disodium-N-tallow-beta-iminodipropionate as the dispersing agent, made according to Procedure A of Nottorf, U.S. Ser. No. 94,989, filed March 13, 1961 (U8.

Patent 3,142,568, July 28, 1964). The effective coupling equivalent weights were increased by the addition of this third binder component but still did not become higher than 1750 as shown in Table II below. The thickness, 6, still was no greater than 12.5 microns and definition, as determined by projection of 8-mm. film, remained essentially equivalent to the commercial control without integral color-formers.

The flexibilities of Film 1 of Example II and of the above coating were compared in terms of their crack diameters following the testing procedure described by P. Z. Adelstein, Photographic Science and Engineering, vol. 1, No. 2, October 1957, pp. 6368. In a dry atmosphere (10 to 15% relative humidity) the former film was found to have a crack diameter of 0.7 inch while the latter (because of the addition of the polyethyl acrylate flexibilizer) had a crack diameter of only 0.3 inch.

Other coatings were made in which the disodium-N- tallow-beta-iminodipropionate dispersant for polyethyl acrylate was replaced with sodium lauryl sulfate. The flexibility improvement was similar to that found before. Dispersions of polybu-tylacrylate and poly-2-ethylhexylacrylate, prepared similarly by emulsion polymerization, with disodium-N-tallow-beta-iminodipropionate as a dispersing agent, performed in equivalent fashion to the polyethylacrylate latex in improving flexibility of blended gelatin and polyanion color-former binder.

It was found that the replacement of half the gelatin by dispersed polyethylacrylate in the non-photographic layers, viz., the abrasion, filter, and separator layers, decreased the total emulsion cracking diameter by less than 0.1".

EXAMPLE IV The advantages of high sulfite content of the color developer solution were demonstrated by comparing film strips of Film 1 of Example II with strips from two other films which differed only in the amounts of the magenta emulsion coated as layer (b). The low coating weight film had a silver halide coating weight of 24 rng./dm. in the magenta layer, Film 1 of Example II had a silver halide coating weight of 34 mg./dm. and the high coating weight film had a silver halide coating weight of 40 mg./ dm. The film strips from the three films were exposed and processed as described in Example II except for the variation in concentration of the color-developing agent and of the anhydrous sodium sulfite in the color developing solution.

It will be noted that in order to obtain approximately equivalent maximum densities of the magenta dye image it is necessary to balance the higher sulfite. content developer with a higher coating Weight in the magenta layer. In addition to the improvement in grain, it was found that higher sulfite concentration caused a lowering of color contamination, particularly resulting in brighter reds.

Other flexibilizing materials include polyethylene dispersed with oleic acid and suitable neutralizing amine, the butadiene/acrylonitrile polymers of US. 2,836,494, and the polymers of Potter et al. US. 2,376,005.

Although this invention is particularly applicable to negative and reversal color films which are designed for exposure in a camera, it is also useful in other color films which may have other than the conventional layer arrangements. The thin layers made possible by this invention can be used advantageously in negative, positive or reversal color films which may be for cine or still use, in transparencies, prints for viewing by reflected light, intermediate films, etc.

The invention, moreover, is not limited to the specific light-sensitive material described in the above detailed examples. Various other simple and mixed silver halides may be used as the light-senitive materials in like manner. Mixtures of silver bromides, chlorides, and/ or iodides can be made by adding mixtures of soluble salts of these halides in like manner. Other useful soluble halides include calcium bromide, potassium iodide, sodium and potassium chlorides and iodides, etc.

Inert ingredients, e.g., pigments, colloidal silver, polymer latices, matting agents, etc. may be present in all of the element layers including the support. The element may also contain chemical sensitizers, optical sensitizers, coating aid-s, anti-foggants, non-halation dyes and pigments, brightening agents as known to the art, etc.

With this invention it is possible to combine in a single multilayer color photographic element the advantages of the integral color-former structure (ease of processing) with the advantages of superior sharpness, definition, resolution, etc., normally associated with a non-integral colorformer structure. The advantages of sharpness, etc., are not inherent in the non-integral color-former structure except inasmuch as it has been impossible, prior to the present invention, to achieve, in a satisfactory manner, the same thinness of emulsion layers in elements containing integral color-formers.

The elements of this invention possess many advantages in physical properties, especially in that preferred embodiment involving the tri-component binder system for silver halide grains as described in Example III. Such elements are unusually tough, particularly when Wet, and are able to undergo treatment in aqueous processing solutions with excellent resistance to abrasion. With their good flexibility, the emulsion have little tendency to crack, even at low relative humidity. Mounted transparencies, prepared from these elements after exposure and photographic processing, possess a unique superiority in projection in that they do not pop due to the heat of the projection lamp; thus the annoying requirement of changing the focus of the projection lens is eliminated. The tendency of this film to curl at the edges has been reduced to a low level.

What is claimed is:

1. A multilayer photographic, camera-speed film for color photography comprising a film support bearing, in order (1) a red-sensitive silver halide emulsion layer,

(2) a green-sensitive silver halide emulsion layer,

(3) a yellow filter layer, and

(4) a blue-sensitive silver halide emulsion layer,

said emulsion layers having an integral thickness, 6, of not more than 12.5 microns and containing a Water-permeable colloid binder comprising gelatin and a compatible, water-soluble color forming vinyl addition copolymer containing a plurality of color-coupling nuclei of a monomer containing a nucleous capable of forming a dye selected from the group consisting of quinoneimine and azomethine dyes upon color-coupling development of an exposed silver salt image, the color-forming addition copolymers of the respective red-, green-, and blue-sensitive layers being of a 1-hydroxy-N-(B-vinyloxyethyl)-2-naphthamide, a l-phenyl-3-methacrylamido-S-pyrazolone and a methacrylamidobenzoylacetanilide, respectively;

(a) the color-forming addition polymer having an equivalent weight from 350 to 610 and containing water soluble anionic groups, so that the polymer remains in solution in water at 25 C. and at pH 7.0 to the extent of at least 40 grams per liter at a viscosity of 1.5 to 15 centistokes, there being present at least one such anionic group for each color-former nucleus;

(b) the etfective color-forming equivalent weight of the binder for each emulsion layer being not more than 1750; and

(0) there being present in each emulsion layer about 7 to 25 parts by weight of the colorforming polymer and about 10 to 30 parts by Weight of gelatin.

2. An element according to claim 1 wherein said support is a transparent, flexible film.

3. An element according to claim 1 wherein said support is a transparent, flexible film and there is an antihalation layer between said support and the adjacent lightsensitive silver halide emulsion layer.

References Cited by the Examiner UNITED STATES PATENTS 2,380,033 7/45 Dorough et a1 96100 2,423,460 7 47 McQueen 96-91 X 2,463,838 3/49 Wilson 96-114 X 2,489,655 11/49 Martin 961 14 X 2,828,204 3/58 Taylor 96l 14 X 2,976,294 3/61 Firestine 96-114 X 3,070,442 12/62 Cohen et al. 3,073,699 1/ 63 Firestine.

FOREIGN PATENTS 221,880 5/59 Australia.

NORMAN G. TORCHIN, Primary Examiner.

PHILIP E. MANGAN, Examiner. 

1. A MULTILAYER PHOTOGRAPHIC, CAMERA-SPEED FILM FOR COLOR PHOTOGRAPHY COMPRISING A FILM SUPPORT BEARING, IN ORDER (1) A RED-SENSTIVE SILVER HALIDE EMULSION LAYER, (2) A GREEN-SENSITIVE SILVER HALIDE EMULSION LAYER, (3) A YELLOW FILTER LAYER, AND (4) A BLUE-SENSITIVE SILVER HALIDE EMULSION LAYER, SAID EMULSION LAYERS HAVING AN INTEGRAL THICKNESS, $, OF NOT MORE THAN 12.5 MICRONS AND CONTAINING A WATER-PERMEABLE COLLOID BINDER COMPRISING GELATIN AND A COMPATIBLE, WATER-SOLUBLE COLOR FORMING VINYL ADDITION COPOLYMER CONTAINING A PLURALITY OF COLOR-COUPLING NUCLEI OF A MONOMER CONTAINING A NUCLEOUS CAPABLE OF FORMING A DYE SELECTED FROM THE GROUP CONSISTING OF QUINONEIMINE AND AZOMETHINE DYES UPON COLOR-COUPLING DEVELOPMENT OF AN EXPOSED SILVER SALT IMAGE, THE COLOR-FORMING ADDITION COPOLYMERS OF THE RESPECTIVE RED-, GREEN-, AND BLUE-SENSITIVE LAYERS BEING OF A 1-HYDROXY-N-(B-VINYLOXYEHTYL)-2-NAPHTHAMIDE, A 1-PHENYL-3-METHACRYLAMIDE-5-PYRAZOLONE AND A METHACRYLAMIDOBENZOYLACETANILIDE, RESPECTIVELY; (A) THE COLOR-FORMING ADDITION POLYMER HAVING AN EQUIVALENT WEIGHT FROM 350 TO 610 AND CONTAINING WATER SOLUBLE ANIONIC GROUPS, SO THAT THE POLYMER REMAINS IN SOLUTION IN WATER AT 25*C. AND AT PH 7.0 TO THE EXTENT OF AT LEAST 40 GRAMS PER LITER AT A VISVISCOSITY OF 1.5 TO 15 CENTISTOKES, THERE BEING PRESENT AT LEAST ONE SUCH ANIONIC GROUP FOR EACH COLOR-FORMER NUCLEUS; (B) THE EFFECTIVE COLOR-FORMING EQUIVALENT WEIGHT OF THE BINDER FOR EACH EMULSION LAYER BEING NOT MORE THAN 1750; AND (C) THERE BEING PRESENT IN EACH EMULSION LAYER ABOUT 7 TO 25 PARTS BY WEIGHT OF THE COLORFORMING POLYMER AND ABOUT 10 TO 30 PARTS BY WEIGHT OF GELATIN. 